Material for gland packing and the gland packing

ABSTRACT

A reinforcing member made from a fibrous material and disposed at least on one face of a strip-like expanded graphite to form a strip-like base member. The base member is stranded to be formed as a cord-like member. At this time, one side end edge of the base member is placed on the outer peripheral surface of the cord-like member, and, in the side end edge, the strip-like expanded graphite is more elongated in the width direction than the reinforcing member. The stranding of the base member is applied while the strip-like expanded graphite which is elongated in the width direction is placed on the inner side, and the reinforcing member which is short in the width direction is placed on the outer side. According to the configuration, both the reinforcing member and the strip-like expanded graphite are placed in a spiral manner to be alternately arranged in the axial direction on the outer peripheral surface of the cord-like member.

TECHNICAL FIELD

The present invention relates to a gland packing material which isuseful in production of a gland packing, and also to a gland packingwhich is produced by the gland packing material.

BACKGROUND ART

Conventionally, as a gland packing material which is useful inproduction of a gland packing, for example, known are a materialdisclosed in Japanese Patent Publication No. 6-27546 (hereinafter,referred to as conventional art 1), and that disclosed in JapanesePatent No. 2,583,176 (hereinafter, referred to as conventional art 2).

In conventional art 1 above, as shown in FIG. 35, for example, tape-likeexpanded graphite (51) is folded along longitudinal fold lines to form acord-like member (52), and the cord-like member (52) is covered by areinforcing member (53) configured by a knitted or braided member ofmetal wires such as stainless steel, inconel, or monel, thereby forminga gland packing material (50).

In conventional art 2 above, as shown in FIG. 36, for example, acord-like member (52) of tape-like expanded graphite (51) is covered bya reinforcing member (53) configured by a knitted or braided member ofmetal wires, and the resulting member is folded to a V-like shape alonga longitudinal fold line, thereby forming a gland packing material (50).

In both the gland packing materials (50) of the conventional art, theoutside of the cord-like member (52) is reinforced by the reinforcingmember (53) configured by a knitted or braided member of metal wires(hereinafter, such reinforcement is referred to as externalreinforcement) Therefore, the gland packing materials (50) are providedwith high tensile strength. Consequently, a plurality of such glandpacking materials (50) are bundled, and then subjected to a braiding ortwisting process, so that a gland packing can be produced. Inconventional art 1 above, when eight gland packing materials (50) arebundled and an eight-strand square-knitting process is conducted, forexample, a gland packing (54) which is braided as shown in FIG. 37 isproduced, and, when six gland packing materials (50) are bundled and atwisting process is conducted, a gland packing (54) which is twisted asshown in FIG. 38 is produced. In conventional art 2 above, when eightgland packing materials (50) are bundled and an eight-strandsquare-knitting process is conducted, for example, a gland packing (54)which is braided as shown in FIG. 39 is produced, and, when six glandpacking materials (50) are bundled and a twisting process is conducted,a gland packing (54) which is twisted as shown in FIG. 40 is produced.

Each of the conventional gland packings (54) is provided by the expandedgraphite (51) with properties which are preferable in sealing, and whichare inevitable in a packing, such as the heat resistance, thecompressibility, and the recovery property, and hence can seal a shaftseal part of a fluid apparatus while producing a high sealing property.

On the other hand, as a further gland packing material which is usefulin production of a gland packing, for example, known is a materialdisclosed in Japanese Patent No. 3,101,916 (hereinafter, referred to asconventional art 3).

In conventional art 3, as shown in FIG. 41, for example, both faces of areinforcing member (53) configured by plural carbon fibers are coveredby expanded graphite (51), thereby forming a gland packing material (50)in which the interior is reinforced (hereinafter, such reinforcement isreferred to as internal reinforcement).

The gland packing material (50) is provided with high tensile strengthby the reinforcing member (53) configured by the carbon fibers, andhence can be subjected to a braiding or twisting process. When aplurality of such gland packing materials (50) are bundled, and then abraiding or twisting process is applied to the bundle, therefore, agland packing can be produced. When eight gland packing materials (50)are bundled and an eight-strand square-knitting process is conducted,for example, a gland packing (54) which is braided as shown in FIG. 37is produced, and, when six gland packing materials (50) are bundled anda twisting process is applied, a gland packing (54) which is twisted asshown in FIG. 38 is produced.

Each of the conventional gland packings (54) is provided by the expandedgraphite (51) with properties which are preferable in sealing, and whichare inevitable in a packing, such as the compressibility and therecovery property, and hence can seal a shaft seal part of a fluidapparatus while producing a high sealing property.

In the gland packing material (50) having the external reinforcementstructure disclosed in conventional art 1 or 2, however, the cord-likemember (52) of the expanded graphite (51) is covered by the reinforcingmember (53). Therefore, the gland packing material can obtain anexcellent shape-retaining property, but has a drawback that the sealingproperty is poor. By contrast, in the gland packing material (50) havingthe internal reinforcement structure disclosed in conventional art 3,the surface of the reinforcing member (53) is covered by the expandedgraphite (51). Therefore, the gland packing material can obtain anexcellent sealing property, but has a drawback that the shape-retainingproperty is poor. In the gland packing (54) which is produced bybundling a plurality of the gland packing materials (50) having the poorsealing property and then applying a braiding or twisting process to thebundle, it is not expected to exert a high sealing property. In thegland packing (54) which is produced by bundling a plurality of glandpacking materials (50) having the poor shape-retaining property and thenapplying a braiding or twisting process to the bundle, there is apossibility that the expanded graphite (51) drops off during thebraiding or the twisting process, the elasticity of the gland packing(54) is reduced, the properties which are preferable in sealing, such asthe compressibility and the recovery property are lost, and the sealingproperty of the gland packing (54) is lowered.

The invention has been developed in view of the above-describedcircumstances. It is an object of the invention to provide a glandpacking material which is provided with high tensile strength by areinforcing member to be easily subjected to a braiding or twistingprocess, and which has both an excellent shape-retaining property thatis possessed by a gland packing material having the externalreinforcement structure, and an excellent sealing property that ispossessed by a gland packing material having the internal reinforcementstructure, and a gland packing which is produced with using the glandpacking material.

DISCLOSURE OF THE INVENTION

In order to attain the object, for example, the invention is configuredin the manner which will be described with reference to FIGS. 1 to 34showing embodiments of the invention.

Namely, the invention relates also to a gland packing material, and ischaracterized in that the material is configured by a cord-like member(40) which is formed by stranding a strip-like base member (4), orwinding a strip-like base member (4) about a longitudinal direction, orwinding a strip-like base member (4) about a longitudinal direction andthen stranding the base member, the base member (4) comprises: areinforcing member (20) configured by a fibrous material (2); and astrip-like expanded graphite (3), the reinforcing member (20) isdisposed at least on one face of the strip-like expanded graphite (3),and both the reinforcing member (20) and the strip-like expandedgraphite (3) are placed on an outer peripheral surface of the cord-likemember (40).

The invention relates to a gland packing, and is characterized in that aplurality of the gland packings (1) are used, and braided or twisted.

According to the configuration, the invention has the followingadvantages.

The cord-like member is surely reinforced by the reinforcing memberconfigured by the fibrous material. The strip-like expanded graphite hasproperties which are preferable in sealing, and which are inevitable ina packing, such as the heat resistance, the compressibility, and therecovery property. Since the reinforcing member and the strip-likeexpanded graphite are placed on the outer peripheral surface of thecord-like member, an excellent shape-retaining property can be ensuredby the reinforcing member, and an excellent sealing property can beensured by the strip-like expanded graphite. Therefore, the glandpacking material can satisfactorily exert both the functions of theshape-retaining property and the sealing property.

Consequently, in the gland packing which is produced with using aplurality of the gland packing materials, the expanded graphite isprevented from dropping off during the braiding or the twisting process,the elasticity is not reduced, and the properties which are preferablein sealing, such as the compressibility and the recovery property can beheld. In the case where the packing is compressed or a pressure isapplied to the packing, movement of expanded graphite particles issuppressed. Therefore, the sealing face pressure is prevented from beinglowered, so that the pressure resistance performance can be improved,and the pressure contact force to be applied to the counter member iskept to a high level, so that the sealing property can be improved. As aresult, the gland packing can satisfactorily seal a shaft seal part of afluid apparatus or the like.

For example, the gland packing material in which both the reinforcingmember and the strip-like expanded graphite are placed on the outerperipheral surface of the cord-like member can be configured in thefollowing manner.

One side end edge of the base member is placed on an outer peripheralsurface of the cord-like member. In the side end edge, one of thereinforcing member and the strip-like expanded graphite is moreelongated in a width direction than another member. While the one memberwhich is elongated in the width direction is placed on an inner side,and the other member which is short in the width direction is placed onan outer side, the base member is stranded, or the base member isstranded after the base member is wound about the longitudinaldirection. As a result, the reinforcing member and the strip-likeexpanded graphite are placed in a spiral manner to be alternatelyarranged in an axial direction on the outer peripheral surface of thecord-like member.

Alternatively, the gland packing material may be configured in thefollowing manner.

The reinforcing member is formed to be smaller in width than thestrip-like expanded graphite, and a plurality of the reinforcing membersare disposed at least on one face of the strip-like expanded graphitewith forming intervals therebetween in the width direction. While thesmall-width reinforcing members are placed on an outer side, the basemember is stranded, or the base member is stranded after the base memberis wound about the longitudinal direction. As a result, the reinforcingmembers and the strip-like expanded graphite are placed in a spiralmanner to be alternately arranged in an axial direction on the outerperipheral surface of the cord-like member.

Alternatively, the gland packing material may be configured in thefollowing manner.

The base member is stranded about an intermediate portion in a widthdirection of the base member, or the base member is stranded after thebase member is wound about the longitudinal direction in an intermediateportion in the width direction of the base member, thereby causing bothside end edges of the base member to be positioned on an outerperipheral surface of the cord-like member. In one of the side endedges, the reinforcing member is placed on an outer side, and, inanother side end edge, the strip-like expanded graphite is placed on anouter side. As a result, the reinforcing member and the strip-likeexpanded graphite are placed in a spiral manner to be alternatelyarranged in an axial direction on the outer peripheral surface of thecord-like member.

Alternatively, the gland packing material may be configured in thefollowing manner.

The reinforcing member is placed on the outer peripheral surface of thecord-like member. A large number of openings are formed in thereinforcing member. The strip-like expanded graphite enters theopenings, and is exposed from the outer peripheral surface of thecord-like member through the openings. As a result, the outer peripheralsurface of the cord-like member has a mixed structure of the reinforcingmember and the strip-like expanded graphite in which the strip-likeexpanded graphite is randomly dispersed in the reinforcing member.

The reinforcing member may be disposed only on one face of thestrip-like expanded graphite, or may be disposed on both faces of thestrip-like expanded graphite. In the case where the reinforcing memberis disposed on both the faces of the strip-like expanded graphite, aninvolved amount of the reinforcing members which are involved in thecord-like member is increased, and the cord-like member can be stronglyreinforced also from the inner side. Therefore, the tensile strength ofthe gland packing material is further enhanced.

Usually, the fibrous material is formed into a sheet-like shape. Forexample, the fibrous material sheet may be configured by a fiber-openedsheet in which multifilament yarns are opened in a sheet-like shape.

In this case, a thickness of the fiber-opened sheet is preferably set to10 μm to 300 μm, and more preferably to 30 μm to 100 μm. According tothe configuration, the fiber-opened sheet can be easily produced, andthe sheet can be easily stranded, so that the external reinforcementeffect can be enhanced, and leakage from a reinforcing member portioncan be prevented from occurring.

As the fibrous material, one or two or more selected from the groupconsisting of carbon fibers and other brittle fibers, and tough fibersmay be used. These fibrous materials exert a higher sealing property asthe thickness of one fiber is smaller. When each fiber is excessivelythin, the fibrous material may be broken during a stranding process,and, when each fiber is excessively thick, the fibrous material ishardly stranded. Therefore, the diameter of each fiber is preferably 3μm to 15 μm, and more preferably in a range of 5 μm to 9 μm.

In the case where carbon fibers or brittle fibers are used as thefibrous material, as compared with a case where metal wires are used,there is no fear that the gland packing forms a large scratch on acounter member, and the sliding resistance is so low that the rotationperformance or axial sliding performance of the counter member can beimproved, and an excellent heat resistance can be attained. In the casewhere carbon fibers are used, particularly, these performances can beexerted more satisfactorily. In the case where other brittle fibers areused, the invention can be economically implemented.

Specific examples of the brittle fibers are glass fibers, silica fibers,and ceramic fibers such as alumina and alumina-silica. One or two ormore selected from the group consisting of these fibers can be used.

In the case where tough fibers are used as the fibrous material, thefibrous material can be easily produced with using thin fibers becausethe fibers have high bendability and exert excellent workability. Aneconomical gland packing material can be provided because the fibershave high productivity. When such a gland packing material is used, notonly a gland packing having a large diameter, but also a gland packinghaving a small diameter can be easily produced, and moreover it ispossible to produce a gland packing which has high durability, and whichis economical.

Furthermore, specific examples of the tough fibers are metal fibers,aramid fibers, and PBO (poly-p-phenylenebenzobisoxazole) fibers. One ortwo or more selected from the group consisting of these fibers can beused.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 21 show embodiments of the invention.

FIGS. 1 to 4 show a first embodiment of the gland packing material ofthe invention, FIG. 1 is a perspective view of the gland packingmaterial, FIG. 2 is a perspective view showing a fiber bundle, FIG. 3 isa perspective view showing a fiber-opened sheet, and FIG. 4 is aperspective view of a base member.

FIG. 5 is a perspective view of strip-like expanded graphite in a statewhere a small amount of adhesive agent is used, and showing amodification of a procedure of producing the base member.

FIGS. 6 and 7 show another modification of the procedure of producingthe base member, FIG. 6 is a section view showing a first step of theprocedure of forming the base member, and FIG. 7 is a section viewshowing a second step of the procedure of forming the base member.

FIGS. 8 to 13 show modifications of the first embodiment, FIG. 8 is asection view of a base member in a first modification, FIG. 9 is asection view of a base member in a second modification, FIG. 10 is asection view of a base member in a third modification, FIG. 11 is aperspective view of a gland packing material in the third modification,FIG. 12 is a section view of a base member in a fourth modification, andFIG. 13 is a section view of a base member in a fifth modification.

FIGS. 14 to 16 show a second embodiment of the gland packing material ofthe invention, FIG. 14 is a perspective view of the gland packingmaterial, FIG. 15 is a perspective view showing a reinforcing member,and FIG. 16 is a perspective view of a base member.

FIG. 17 is a perspective view of strip-like expanded graphite in a statewhere a small amount of adhesive agent is used, and showing amodification of a procedure of producing the base member in the secondembodiment.

FIGS. 18 to 20 show modifications of the second embodiment, FIG. 18 is asection view of a base member in a first modification, FIG. 19 is aperspective view of a gland packing material in the first modification,and FIG. 20 is a section view of a base member in a second modification.

FIGS. 21 and 22 show a third embodiment of the gland packing material ofthe invention, FIG. 21 is a perspective view of the gland packingmaterial, and FIG. 22 is a perspective view of a base member.

FIGS. 23 and 24 show modifications of a base member in the thirdembodiment, FIG. 23 is a section view of a base member in a firstmodification, and FIG. 24 is a section view of a base member in a secondmodification.

FIGS. 25 to 29 show a fourth embodiment of the gland packing material ofthe invention, FIG. 25 is a perspective view of the gland packingmaterial, FIG. 26 is a partial enlarged plan view showing a state wherestrip-like expanded graphite enters many openings of a reinforcingmember, FIG. 27 is a section view taken along the line A-A in FIG. 26,FIG. 28 is a section view showing a first step of a procedure of shapinga base member, and FIG. 29 is a section view showing a second step ofthe procedure of shaping the base member.

FIGS. 30 to 32 show modifications of the fourth embodiment, FIG. 30 is aperspective view of a gland packing material in a first modification,FIG. 31 is a section view of a base member in a second modification, andFIG. 32 is a perspective view of a gland packing material in the secondmodification.

FIG. 33 is a perspective view showing an embodiment of the gland packingof the invention.

FIG. 34 is a perspective view showing another embodiment of the glandpacking of the invention.

FIGS. 35 to 41 show conventional arts.

FIG. 35 is a perspective view of a gland packing material ofconventional art 1, and FIG. 36 is a perspective view of a gland packingmaterial of conventional art 2.

FIG. 37 is a perspective view of a gland packing which is formed bybraiding the gland packing material of conventional art 1, and FIG. 38is a perspective view of a gland packing which is formed by twisting thegland packing material of conventional art 1.

FIG. 39 is a perspective view of a gland packing which is formed bybraiding the gland packing material of conventional art 2, and FIG. 40is a perspective view of a gland packing which is formed by twisting thegland packing material of conventional art 2.

FIG. 41 is a perspective view of a gland packing material ofconventional art 3.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the invention will be describedwith reference to the drawings.

First Embodiment

FIGS. 1 to 4 show a first embodiment of the gland packing material ofthe invention, and FIG. 1 is a perspective view of the gland packingmaterial. Referring to FIG. 1, the gland packing material (1) isconfigured by a cord-like member (40) which is formed by sequentiallystranding a strip-like base member (4) in the longitudinal directionwith starting from an end. The base member (4) comprises: a sheet-likereinforcing member (20) configured by many long carbon fibers (2) whichare very thin; and a strip-like expanded graphite (3). The reinforcingmember (20) is disposed on one face of the strip-like expanded graphite(3). In the base member (4), one side end edge is placed on an outerperipheral surface of the cord-like member (40). In the one side endedge, the strip-like expanded graphite (3) which is one member (4 a) ismore elongated in the width direction than the reinforcing member (20)which is another member (4 b).

Namely, as shown in FIG. 4, in one side end edge of the base member (4),the reinforcing member (20) and the strip-like expanded graphite (3)overlap with each other, but, in the other side end edge, the strip-likeexpanded graphite (3) is more elongated in the width direction than thereinforcing member (20). As a result of the abovementioned strandingprocess, the other side end edge is placed on the outer peripheralsurface of the cord-like member (40).

The stranding process is applied so that the strip-like expandedgraphite (3) which is the one member (4 a) that is elongated in thewidth direction is placed on the inner side, and the reinforcing member(20) which is the other member (4 b) that is short in the widthdirection is placed on the outer side. As shown in FIG. 1, therefore,the gland packing material (1) has a structure in which the reinforcingmember (20) and the strip-like expanded graphite (3) are stranded in aspiral manner so as to be alternately arranged in the axial direction onthe outer peripheral surface of the cord-like member (40).

The carbon fibers (2) have a property that they are hardly broken by anexternal force of the level of stranding. Therefore, it is possible toobtain the gland packing material (1) having a structure in which thesheet-like reinforcing member (20) configured by the carbon fibers (2)and the strip-like expanded graphite (3) are stranded in a spiral mannerso as to be alternately arranged in the axial direction on the outerperipheral surface of the cord-like member (40). Because of thestructure, an excellent shape-retaining property is ensured by thesheet-like reinforcing member (20), and an excellent sealing property isensured by the strip-like expanded graphite (3). Therefore, the glandpacking material (1) can satisfactorily exert both the functions of theshape-retaining property and the sealing property.

Also when the stranding process is applied after the strip-like basemember (4) is wound about the longitudinal direction, a gland packingmaterial (1) having an appearance and structure which are similar tothose described above can be formed, and the material can function andattain effects in a similar manner as the above-described material.

For example, the gland packing material (1) can be produced in thefollowing procedure.

First, the base member (4) is formed in the following procedure.

As shown in FIG. 2, initially, a multifilament yarn in which, forexample, 12,000 carbon fibers (2) each having a diameter of 7 μm arebundled is used to form a fiber bundle (2A) in which the fibers arebundled in a flat shape having a width (W)=4.00 mm and a thickness(T)=0.20 mm. Then, the fiber bundle (2A) is fiber-opened to a sheet-likeshape so as to be extended in the width direction, whereby afiber-opened sheet (2B) having a width (W1)=12.00 mm and a thickness(T1)=0.06 mm is formed as shown in FIG. 3.

For example, the fiber opening process is conducted in the followingmanner. First, the fiber bundle (2A) is heated to soften a sizing agentfor the fiber bundle, and the fiber bundle (2A) is fed in thelongitudinal direction while controlling the speed of the fiber bundle.An air flow is blown in a crossing direction while maintaining apredetermined overfeed amount. In a portion where the air flow passes,the fiber bundle (2A) is arcuately strained to be unbound in the widthdirection, and the sizing agent is cooled and hardened, thereby formingthe extended fiber-opened sheet (2B).

As shown in FIG. 4, next, the reinforcing member (20) configured byfiber-opened sheet (2B) is laid on one face of the strip-like expandedgraphite (3) having a width (W3)=24.00 mm and a thickness (T3)=0.25 mm,to form the base member (4) in which the reinforcing member (20)configured by the carbon fibers (2) is disposed on one face of thestrip-like expanded graphite (3). The width (W2) of the reinforcingmember (20) is one half of the width (W3) of the strip-like expandedgraphite (3). In the base member (4), therefore, the strip-like expandedgraphite (3) and the reinforcing member (20) are aligned with each otherin one side end edge, and the strip-like expanded graphite (3) is moreelongated in the width direction than the reinforcing member (20) in theother side end edge.

Then, the base member (4) is stranded to be formed into the cord-likemember (40), thereby producing the gland packing material (1).

Preferably, an adhesive agent is omitted in the base member (4) becauseof the following reasons. When an adhesive agent is omitted, theproperties of the strip-like expanded graphite such as the affinity andthe compression recovery property can be prevented from being lowered byhardening of the adhesive agent, and, even when used under a hightemperature condition, reduction of the sealing property due to burningof the adhesive agent can be prevented from occurring. In the basemember (4), however, the coupling force between the reinforcing member(20) and the strip-like expanded graphite (3) may be enhanced by using asmall amount of adhesive agent. Specifically, as shown in FIG. 5, forexample, an adhesive agent (6) of epoxy resin, acrylic resin, phenolresin, or like resin may be disposed in a spot-like manner on one faceof the strip-like expanded graphite (3) having a width (W3)=24.00 mm anda thickness (T3)=0.25 mm, and the sheet-like reinforcing member (20) maybe laid on one face of the strip-like expanded graphite (3) in thisstate to form the base member (4). The adhesive agent (6) is used in aspot-like manner so that the used amount is restricted to a very smalllevel. Therefore, the properties of the strip-like expanded graphite (3)such as the affinity and the compression recovery property are preventedfrom being lowered by hardening of the adhesive agent (6), and, evenwhen used under a high temperature condition, reduction of the sealingproperty due to burning of the adhesive agent is decreased.

Alternatively, as shown in FIGS. 6 and 7, for example, the base member(4) may be formed by, when expanded graphite powder (3A) is to becompression-molded to the strip-like expanded graphite (3), disposingthe reinforcing member (20) to be integrated with one face of thestrip-like expanded graphite (3). Specifically, as shown in FIG. 6, thereinforcing member (20) having a width (W2)=12.00 mm and a thickness(T2)=0.06 mm is placed in a mold (7), and expanded graphite powder (3A)is superimposed on the reinforcing member. As shown in FIG. 7, acompression-molding process is then applied with using a pressing mold(8), thereby forming the base member (4) in which the sheet-likereinforcing member (20) is disposed on one face of the strip-likeexpanded graphite (3) that is compressed so as to have a width(W3)=24.00 mm and a thickness (T3)=0.25 mm.

It is a matter of course that, in the fibrous material, the reinforcingmember, and the strip-like expanded graphite which are used in theinvention, the thickness of the fibers, the number of the bundledfibers, the width of the sheet, the thickness of the sheet, the widthand thickness of the strip-like expanded graphite, and the like are notrestricted to those in the first embodiment described above.

As the carbon fibers (2), however, it is preferable to use fibers eachhaving a diameter of 3 μm to 15 μm. When the diameter is smaller than 3μm, the fibers may be broken during the stranding process, and, when thediameter is larger than 15 μm, the fibers are hardly stranded. Thecarbon fibers (2) exert a higher sealing property as their diameter issmaller. Therefore, it is most preferable to set the diameter of thecarbon fibers (2) to a range of 5 μm to 9 μm. In the invention, in placeof carbon fibers, other brittle fibers, or tough fibers may be used. Inthe case where tough fibers such as metal fibers are used, such fibershave high bendability, and hence it is less likely that they are brokenduring the stranding process. In such a case, therefore, thinner fibersmay be used.

Moreover, the thickness (T1) of the fiber-opened sheet (2B), i.e., thethickness (T2) of the reinforcing member (20) is preferably set to arange of 10 μm to 300 μm, and more preferably to a range of 30 μm to 100μm. When the thickness (T2) is smaller than 10 μm, the reinforcementeffect is reduced, and a uniform sheet is hardly produced. When thethickness (T2) is larger than 300 μm, the reinforcement effect can beenhanced, but the stranding process is hardly applied and leakage from areinforcing member portion easily occurs.

In the first embodiment, the strip-like expanded graphite (3) is formedso as to be elongated in the width direction in one of side end edges ofthe base member (4). In the invention, in place of the above, thereinforcing member (20) may be formed so as to be elongated in the widthdirection.

In a first modification shown in FIG. 8, the sheet-like reinforcingmember (20) which is configured by the carbon fibers (2), and which iswider than the strip-like expanded graphite (3) is laid on one face ofthe strip-like expanded graphite (3), thereby forming the base member(4). In this case, the reinforcing member (20) is more elongated in thewidth direction than the strip-like expanded graphite (3) in a side endedge of the base member (4). The stranding process is applied while thereinforcing member (20) that is the one member (4 a) which is elongatedin the width direction is placed on the inner side, and the strip-likeexpanded graphite (3) that is the other member (4 b) which is short inthe width direction is placed on the outer side.

In a second modification shown in FIG. 9, the strip-like expandedgraphite (3) and the sheet-like reinforcing member (20) which have thesame width overlap with each other while shifting from each other in thewidth direction, to form the base member (4). When a stranding processis applied to the base member (4), the member is formed into thecord-like member (40). The stranding process is applied so that, in oneside end edge of the base member (4) which is placed on the outerperipheral surface of the cord-like member (40), the member that iselongated in the width direction is placed on the inner side.

FIGS. 10 and 11 show a third modification of the first embodiment of theinvention. In the third modification, as shown in FIG. 10, reinforcingmembers (20) which are smaller in width than the strip-like expandedgraphite (3) are laid respectively on the front and rear of thestriplike expanded graphite (3) so as to be opposed to each other, whilethe reinforcing members are deviated toward one side in the widthdirection of the strip-like expanded graphite (3), thereby forming thebase member (4). When the thus formed base member (4) is stranded orwound to be stranded, it is possible to obtain the gland packingmaterial (1) having a structure in which, as shown in FIG. 11, thereinforcing member (20) and the strip-like expanded graphite (3) arestranded in a spiral manner so as to be alternately arranged in theaxial direction. In the gland packing material (1), an excellentshape-retaining property and an excellent sealing property can beensured. Since an involved amount of the reinforcing members (20) whichare involved in the cord-like member (40) is increased, moreover, theinternal reinforcement can be more strongly applied, and the tensilestrength of the gland packing material (1) is further enhanced.

In a fourth embodiment shown in FIG. 12, reinforcing members (20) whichare smaller in width than the strip-like expanded graphite (3) are laidrespectively on the both faces of the strip-like expanded graphite (3)so as to be deviated from each other on the front and rear of thestrip-like expanded graphite (3), thereby forming the base member (4).When the base member (4) is stranded or wound to be stranded, it ispossible to obtain the gland packing material (1) which is similar tothat of the third modification, and in which the internal reinforcementis strongly applied.

In the third and fourth modifications, the reinforcing members (20)which are disposed respectively on the both faces of the strip-likeexpanded graphite (3) are formed so as to have the same width, and hencethe front and rear of the base member (4) have the same shape.Therefore, the gland packing material (1) using the base member (4) canbe easily produced. In the invention, however, one of the reinforcingmembers (20) which is to be wound into the cord-like member (40) may beformed so as to have the same width as the strip-like expanded graphite(3).

FIG. 13 shows a fifth modification of the first embodiment of theinvention. Strip-like expanded graphites (3•3) which are smaller inwidth than the sheet-like reinforcing member (20) are laid respectivelyon the both faces of the sheet-like reinforcing member (20), to form thebase member (4). In the case where the strip-like expanded graphites (3)are disposed respectively on the both faces of the reinforcing member(20) as in the fifth modification, one of the strip-like expandedgraphites (3) which is on the inner side in the formation of thecord-like member (40) may be formed so as to have the same width as thereinforcing member (20) as indicated by, for example, the phantom linesin FIG. 13.

Second Embodiment

FIGS. 14 to 16 show a second embodiment of the gland packing material ofthe invention, and FIG. 14 is a perspective view of the gland packingmaterial. Referring to FIG. 14, in the same manner as the firstembodiment described above, the gland packing material (1) is configuredby the cord-like member (40) which is formed by sequentially strandingthe strip-like base member (4) in the longitudinal direction withstarting from an end. The base member (4) comprises: the sheet-likereinforcing member (20) configured by the many long carbon fibers (2)which are very thin; and the strip-like expanded graphite (3). Thereinforcing member (20) is disposed on one face of the strip-likeexpanded graphite (3).

The reinforcing member (20) is formed so as to be smaller in width thanthe strip-like expanded graphite (3), and a plurality of the reinforcingmembers are disposed on one face of the strip-like expanded graphite (3)with forming intervals therebetween in the width direction. As shown inFIG. 16, for example, three small-width sheet-like reinforcing members(20) are laid on one face of the strip-like expanded graphite (3) withforming intervals therebetween in the width direction, thereby formingthe base member (4).

The stranding process is applied so that the small-width reinforcingmembers (20) are placed on the outer side. As shown in FIG. 14,therefore, the gland packing material (1) has a structure in which thereinforcing members (20) and the strip-like expanded graphite (3) arestranded in a spiral manner so as to be alternately arranged in theaxial direction on the outer peripheral surface of the cord-like member(40).

The other configuration is similar to that of the first embodiment, andfunctions and attains effects in a similar manner. Therefore, itsdescription is omitted.

Also when the stranding process is applied after the strip-like basemember (4) is wound about the longitudinal direction, a gland packingmaterial (1) having an appearance and structure which are similar tothose described above can be formed, and the material can function andattain effects in a similar manner as the above-described material.

For example, the gland packing material (1) can be produced in thefollowing procedure.

The fiber-opened sheet (2B) which is used in the first embodiment, andwhich is shown in FIG. 3 is divided in the width direction into plural(for example, three) sections, so that, as shown in FIG. 15, threereinforcing members (20) each having a width (W2)=4.00 mm and athickness (T2)=0.06 mm are formed.

As shown in FIG. 16, then, the three reinforcing members (20) are laidon one face of the strip-like expanded graphite (3) having a width(W3)=24.00 mm and a thickness (T3)=0.25 mm, with forming predeterminedintervals (L) therebetween in the width direction of the strip-likeexpanded graphite (3), thereby forming the base member (4) in which thethree reinforcing members (20•20•20) configured by the carbon fibers (2)are disposed on one face of the strip-like expanded graphite (3). Forexample, the predetermined intervals (L) are set to a value which isequal to the width (W2) of the reinforcing members (20). In theinvention, the intervals (L) may be set to a value which is differentfrom the width (W2).

In the same manner as the first embodiment, in the base member (4), thecoupling force between the reinforcing members (20) and the strip-likeexpanded graphite (3) may be enhanced by using a small amount ofadhesive agent. Specifically, as shown in FIG. 17, for example, anadhesive agent (6) of epoxy resin, acrylic resin, or phenol resin may bedisposed in a spot-like manner on the upper face of the strip-likeexpanded graphite (3) having a width (W3)=24.00 mm and a thickness(T3)=0.25 mm, and the three reinforcing members (20•20•20) may be bondedto one face of the strip-like expanded graphite (3) in this state toform the base member (4). With respect to the intervals of the spots ofthe adhesive agent (6), for example, the intervals (L1) in the widthdirection is set to be substantially equal to the width (W2) of thereinforcing member (20), and the intervals (L2) in the longitudinaldirection is set to a value which is larger than the intervals (L1) inthe width direction. However, the intervals are not restricted to thesevalues.

In the same manner as the first embodiment, the base member (4) may beformed by, when expanded graphite powder is to be compression-molded tothe strip-like expanded graphite (3), disposing the reinforcing members(20) to be integrated with one face of the strip-like expanded graphite(3).

In the second embodiment, the sheet-like reinforcing member (20) isdisposed on one face of the strip-like expanded graphite (3). In theinvention, alternatively, the sheet-like reinforcing member (20) may bedisposed on the both faces of the strip-like expanded graphite (3).

In a first modification shown in FIG. 18, for example, three reinforcingmembers (20) are laid on each of the faces of the strip-like expandedgraphite (3) with forming predetermined intervals (L) therebetween inthe width direction of the strip-like expanded graphite (3), and atpositions of the front and rear of the strip-like expanded graphite (3)which are opposed to each other. Specifically, six reinforcing members(20 . . . ) configured by the carbon fibers (2) are disposed on the bothfaces of the strip-like expanded graphite (3) to form the base member(4). When the base member (4) is stranded or wound to be stranded, it ispossible to obtain the gland packing material (1) having a structure inwhich, as shown in FIG. 19, the reinforcing members (20) configured bythe carbon fibers (2), and the strip-like expanded graphite (3) arealternately arranged in the axial direction and stranded in a spiralmanner. In the gland packing material (1), an excellent shape-retainingproperty and an excellent sealing property can be ensured. Since aninvolved amount of the reinforcing members (20) which are involved inthe cord-like member (40) is increased, moreover, the internalreinforcement can be more strongly applied, and the tensile strength ofthe gland packing material (1) is further enhanced.

In a second modification shown in FIG. 20, the three reinforcing members(20) are laid on each of the faces of the strip-like expanded graphite(3), with forming the predetermined intervals (L) therebetween in thewidth direction of the strip-like expanded graphite (3), and atpositions of the front and rear of the strip-like expanded graphite (3)which are deviated from each other. Also when the base member (4) isstranded or wound to be stranded, it is possible to obtain the glandpacking material (1) in which the internal reinforcement is stronglyapplied in the same manner as the first modification.

In the modifications described above, the reinforcing members (20) whichare disposed on the both faces of the strip-like expanded graphite (3)are formed so as to have the same width, and hence the front and rear ofthe base member (4) have the same shape. Therefore, the gland packingmaterial (1) using the base member (4) can be easily produced. In theinvention, however, one of the reinforcing members (20) which isdisposed on the one face that is to be wound into the cord-like member(40) may be formed so as to have the same width as the strip-likeexpanded graphite (3). According to the configuration, the reinforcementeffect due to the reinforcing members (20) can be further enhanced.

Third Embodiment

FIGS. 21 and 22 show a third embodiment of the gland packing material ofthe invention, and FIG. 21 is a perspective view of the gland packingmaterial. Referring to FIG. 21, in the same manner as the first andsecond embodiments described above, the gland packing material (1) isconfigured by the cord-like member (40) which is formed by sequentiallystranding the strip-like base member (4) in the longitudinal directionwith starting from an end, or winding the strip-like base member (4)about the longitudinal direction and then stranding the member. As shownin FIG. 22, for example, the base member (4) comprises: the sheet-likereinforcing member (20) configured by the many long carbon fibers (2)which are very thin; and the strip-like expanded graphite (3) which hasthe same width as the member. The reinforcing member (20) is disposed onone face of the strip-like expanded graphite (3).

The stranding process is applied about an intermediate portion in thewidth direction of the base member (4) so that the section shape isformed into, for example, an S-like shape, or applied after thestrip-like base member (4) is wound about the longitudinal direction inan intermediate portion in the width direction of the base member (4).Therefore, the both side end edges of the base member (4) are positionedon the outer peripheral surface of the cord-like member (40), and, inone of the side end edges, the reinforcing member (20) is placed on theouter side, and, in the other side end edge, the strip-like expandedgraphite (3) is placed on the outer side. As a result, the gland packingmaterial (1) has a structure in which, as shown in FIG. 21, thereinforcing member (20) and the strip-like expanded graphite (3) arestranded in a spiral manner so as to be alternately arranged in theaxial direction on the outer peripheral surface of the cord-like member(40).

The other configuration is similar to that of the first and secondembodiments, and functions and attains effects in a similar manner.Therefore, its description is omitted.

In the third embodiment, the reinforcing member (20) is disposed only onone face of the strip-like expanded graphite (3). Alternatively, as in afirst modification shown in FIG. 23, for example, the reinforcing member(20) may be disposed on each of the strip-like expanded graphite (3). Inthis case, one of the reinforcing members (20) (the upper side one inFIG. 23) is formed so that one side end edge is shorter than thestrip-like expanded graphite (3), thereby causing the strip-likeexpanded graphite (3) in the side end edge to be placed in the surfaceof the cord-like member (40).

In a second modification of the third embodiment shown in FIG. 24, thestrip-like expanded graphite (3) is disposed on each of the faces of thesheet-like reinforcing member (20). In this case, one of the strip-likeexpanded graphites (3) (the lower side one in FIG. 24) is formed so thatone side end edge is shorter than the reinforcing member (20), therebycausing the reinforcing member (20) in the side end edge to be placed inthe surface of the cord-like member (40).

Fourth Embodiment

FIGS. 25 to 29 show a fourth embodiment of the gland packing material ofthe invention, and FIG. 25 is a perspective view of the gland packingmaterial. Referring to FIG. 25, in the same manner as the embodimentsdescribed above, the gland packing material (1) is configured by thecord-like member (40) which is formed by sequentially stranding thestrip-like base member (4) in the longitudinal direction with startingfrom an end. The base member (4) comprises: the sheet-like reinforcingmember (20) configured by the many long carbon fibers (2) which are verythin; and the strip-like expanded graphite (3). The reinforcing member(20) is disposed on one face of the strip-like expanded graphite (3).

The reinforcing member (20) is placed on the outer peripheral surface ofthe cord-like member (40). As shown in FIG. 26, a large number ofopenings (20A . . . ) are formed in the reinforcing member (20). Asshown in FIG. 27, the strip-like expanded graphite (3) enters theopenings (20A) to be exposed flushly or substantially flushly from theouter peripheral surface of the cord-like member (40) through theopenings (20A). As shown in FIG. 25, therefore, the strip-like expandedgraphite (3) is randomly dispersed in the surface of the reinforcingmember (20) configured by the carbon fibers (2) which are placed in theouter peripheral surface of the cord-like member (40), so that thesurface of the gland packing material (1) has a mixed structure of thereinforcing member (20) and the strip-like expanded graphite (3).According to the configuration, an excellent shape-retaining property isensured by the sheet-like reinforcing member (20), and an excellentsealing property is ensured by the strip-like expanded graphite (3).Therefore, the gland packing material (1) can satisfactorily exert boththe functions of the shape-retaining property and the sealing property.

The large number of openings (20A . . . ) can be configured by manylocal clefts which are formed by slightly forcedly tearing in anartificial manner many portions of the reinforcing member (20)configured by the many long carbon fibers (2) that are very thin, insuch a manner that adjacent carbon fibers (2) are separated from eachother.

For example, the gland packing material (1) can be produced in thefollowing procedure.

First, the base member (4) is formed in the following procedure.

Initially, the sheet-like reinforcing member (20) configured by carbonfibers is formed in the same manner as the first embodiment. Then, manyportions of the reinforcing member (20) are slightly forcedly torn in anartificial manner in such a manner that adjacent carbon fibers (2) areseparated from each other, thereby forming many local clefts in thereinforcing member (20). The clefts constitute the openings (20A . . .). The sheet-like reinforcing member (20) comprising the large number ofopenings (20A . . . ) and having a width (W2)=24.00 mm and a thickness(T2)=0.06 mm is placed in the mold (7) as shown in FIG. 28.

Expanded graphite powder (3A) is laid on the sheet-like reinforcingmember (20) which is placed in the mold (7). As shown in FIG. 29,thereafter, a compression-molding process is then applied with using thepressing mold (8), thereby forming the base member (4) in which thereinforcing member (20) configured by the carbon fibers (2) is disposedon one face of the strip-like expanded graphite (3) having a width(W3)=24.00 mm and a thickness (T3)=0.25 mm. As shown in FIGS. 26 and 27,the strip-like expanded graphite (3) enters the openings (20A) to beexposed flushly or substantially flushly from the surface of thereinforcing member (20). Therefore, the base member (4) has a mixedstructure of the reinforcing member (20) and the strip-like expandedgraphite (3) in which the strip-like expanded graphite (3) is randomlydispersed in the surface of the reinforcing member (20) configured bythe carbon fibers (2). A stranding process is applied to the thus formedbase member (4) in a state where the reinforcing member (20) is outwarddirected, and the cord-like member (40) is formed, thereby producing thegland packing material (1).

FIG. 30 shows a first modification of the fourth embodiment. The glandpacking material (1) is configured by the cord-like member (40) which isformed by winding the base member (4) about the longitudinal directionin a state where the reinforcing member (20) is outward directed. In thefirst modification also, the strip-like expanded graphite (3) israndomly dispersed in the surface of the sheet-like reinforcing member(20) which is placed in the surface of the cord-like member (40).Therefore, the surface of the gland packing material (1) has a mixedstructure of the reinforcing member (20) and the strip-like expandedgraphite (3).

The other configuration is similar to that of the fourth embodiment, andfunctions in a similar manner. Therefore, its description is omitted.

When the gland packing material (1) of the first modification is furtherstranded in a spiral manner, the material can be formed into the glandpacking material (1) having an appearance which is identical with thatof the fourth embodiment.

FIGS. 31 and 32 show a second modification of the fourth embodiment.

In the second modification, the reinforcing member (20) configured bythe carbon fibers (2) is disposed on each of the faces of the strip-likeexpanded graphite (3), to configure the base member (4). In the samemanner as the fourth embodiment, the gland packing material (1) isconfigured by the cord-like member (40) which is formed by sequentiallystranding the base member (4) in the longitudinal direction withstarting from an end.

In the gland packing material (1), an excellent shape-retaining propertycan be ensured by the reinforcing member (20) configured by the carbonfibers (2) in the surface side, and an excellent sealing property can beensured by the strip-like expanded graphite (3). Since an involvedamount of the reinforcing members (20) which are involved in thecord-like member (40) is increased, moreover, the internal reinforcementcan be more strongly applied to the gland packing material (1), and thetensile strength of the material can be further enhanced.

In the embodiments described above, carbon fibers are used as thefibrous material. In the invention, alternatively, other brittle fibers,and tough fibers may be used. Examples of such brittle fibers are glassfibers such as E-glass, T-glass, C-glass, and S-glass, silica fibers,and ceramic fibers such as alumina and alumina-silica. Such brittlefibers exhibit a low sliding resistance. Therefore, the rotationperformance or axial sliding performance of the counter member can beimproved, and an excellent heat resistance can be attained.

Examples of the tough fibers are metal fibers such as stainless steel,aramid fibers, and PBO fibers. These tough fibers have high bendability.Therefore, the production of the gland packing material in which thebase member is stranded, wound, or wound to be stranded is facilitated,and hence the productivity is improved. As a result, it is possible toprovide an economical gland packing material, and also to improve thedurability of the gland packing material.

Although a fiber-opened sheet is used as the sheet configured by afibrous material, the fibrous material which is useful in the inventionmay be formed into a sheet-like shape by other means.

Next, the gland packing of the invention which is produced with usingthe gland packing material will be described.

FIG. 33 is a perspective view showing an embodiment of the gland packingof the invention.

The cord-like gland packing (5) is produced by preparing a plurality ofthe above-described gland packing materials (1) of the invention, andbundling and braiding these gland packing materials (1) by a braidingmachine. For example, the gland packing (5) shown in FIG. 33 is producedby conducting an eight-strand square-knitting process on eight glandpacking materials (1).

In the gland packing (5), a plurality of above-described gland packingmaterials (1) are braided, properties which are requested in a packing,and which are preferable in sealing, such as the heat resistance, thecompressibility, and the recovery property are provided by thestrip-like expanded graphite, and a high shape-retaining property isprovided by the reinforcing member (20). Therefore, the gland packing(5) in which a plurality of gland packing materials (1) are braided hasexcellent shape-retaining and sealing properties, and can satisfactorilyseal a shaft seal part of a fluid apparatus.

FIG. 34 is a perspective view showing another embodiment of the glandpacking of the invention.

In the embodiment, the cord-like gland packing (5) is produced by, inplace of braiding gland packing materials (1), bundling and twisting aplurality of above-described gland packing materials (1). For example,the gland packing (5) shown in FIG. 34 is formed by conducting a rollmolding process while bundling and applying a twisting process on sixgland packing materials (1).

The gland packing (5) of the embodiment functions and attains effects ina similar manner as the embodiment in which the gland packing materials(1) are braided. Therefore, its description is omitted.

1. A gland packing material wherein said gland packing materialcomprises a cord member (40) which is formed by stranding a base stripmember (4), or winding a base strip member (4) about a longitudinaldirection; or winding a base strip member (4) about a longitudinaldirection and then stranding said base strip member, said base stripmember (4) comprises: a reinforcing member (20) comprised of a fibrousmaterial (2); and an expanded graphite strip (3), said reinforcingmember (20) is disposed at least on one face of said expanded graphitestrip (3), and both said reinforcing member (20) and said expandedgraphite strip (3) are placed on an outer peripheral surface of saidcord member (40).
 2. A gland packing material according to claim 1,wherein one side end edge of said base strip member (4) is placed on anouter peripheral surface of said cord member (40) in the side end edge,one member (4 a) of said reinforcing member (20) and said expandedgraphite strip (3) is more elongated in a width direction than anothermember (4 b), and said one member (4 a) which is elongated in the widthdirection is placed on an inner side, and said other member (4 b) whichis short in the width direction is placed on an outer side, said basestrip member (4) is stranded after said base strip member is wound aboutthe longitudinal direction, whereby said reinforcing member (20) andsaid expanded graphite strip (3) are placed in a spiral manner to bealternately arranged in an axial direction on the outer peripheralsurface of said cord member (40).
 3. A gland packing material accordingto claim 1, wherein said reinforcing member (20) is formed to be smallerin width than said expanded graphite strip (3), a plurality of saidreinforcing members (20) are disposed at least on one face of saidexpanded graphite strip (3) with intervals formed therebetween in awidth direction, and said smaller in width reinforcing members (20) areplaced on an outer side, said base strip member (4) is stranded altersaid base strip member is wound about the longitudinal direction,whereby said reinforcing members (20) and said expanded graphite strip(3) are wound in a spiral manner to be alternately arranged in an axialdirection on the outer peripheral surface of said cord member (40).
 4. Agland packing material according to claim 1, wherein said base stripmember (4) is stranded after said base strip member is wound about thelongitudinal direction in an intermediate portion in the width directionof said base strip member (4), thereby causing both side end edges ofsaid base strip member (4) to be positioned on an outer peripheralsurface of said cord member (40), in one of said side end edges, saidreinforcing member (20) is placed on an outer side, and, in another sideend edge, said expanded graphite strip (3) is placed on an outer side,whereby said reinforcing member (20) and said expanded graphite strip(3) are placed in a spiral manner to be alternately arranged in an axialdirection on the outer peripheral surface of said card member (40).
 5. Agland packing material according to claim 1, wherein said reinforcingmember (20) is placed on the outer peripheral surface of said cordmember (40), a large number of openings (20A) are formed in saidreinforcing member (20), said expended graphite strip (3) enters saidopenings (20A), and is exposed from the outer peripheral surface of saidcord member (40) through said openings (20A).
 6. A gland packingmaterial according to claim 1, wherein said reinforcing member (20) isdisposed only on one face of said expanded graphite strip (3).
 7. Agland packing material according to claim 1, wherein said reinforcingmember (20) is disposed on both faces of said expanded graphite strip(3).
 8. A gland packing material according to claim 1, wherein saidfibrous material (2) is fanned into a sheet shape, and said fibrousmaterial sheet comprises a fiber-opened sheet (2B) in whichmultifilament yarns are opened in a sheet shape.
 9. A gland packingmaterial according to claim 8, wherein a thickness of said fiber-openedsheet (2B) is set to 10 μm to 300 μm.
 10. A gland packing materialaccording to claim 1, wherein said fibrous material (2) comprises atleast one selected from the group consisting of carbon fibers, brittlefibers, and tough fibers.
 11. A gland packing material according toclaim 10, wherein said brittle fibers comprise at least one selectedfrom the group consisting of glass fibers, silica fibers, and ceramicfibers.
 12. A gland packing material according to claim 10, wherein saidtough fibers comprise at least one selected from the group consisting ofmetal fibers, aramid fibers, and PBO fibers.
 13. A gland packingcomprising braiding or winding together a plurality of gland packingmaterials (1) according to any one of claims 1 to 12.